[wpiutil] Add JNI wrapper for wpi::Now() (#2632)

wpiutil/src/main/native/cpp/jni/WPIUtilJNI.cpp

@@ -1,5 +1,5 @@
 /*----------------------------------------------------------------------------*/
-/* Copyright (c) 2019 FIRST. All Rights Reserved.                             */
+/* Copyright (c) 2019-2020 FIRST. All Rights Reserved.                        */
 /* Open Source Software - may be modified and shared by FRC teams. The code   */
 /* must be accompanied by the FIRST BSD license file in the root directory of */
 /* the project.                                                               */
@@ -10,6 +10,7 @@
 #include "edu_wpi_first_wpiutil_WPIUtilJNI.h"
 #include "wpi/PortForwarder.h"
 #include "wpi/jni_util.h"
+#include "wpi/timestamp.h"
 
 using namespace wpi::java;
 
@@ -25,6 +26,18 @@ JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM* vm, void* reserved) {
 
 JNIEXPORT void JNICALL JNI_OnUnload(JavaVM* vm, void* reserved) {}
 
+/*
+ * Class:     edu_wpi_first_networktables_NetworkTablesJNI
+ * Method:    now
+ * Signature: ()J
+ */
+JNIEXPORT jlong JNICALL
+Java_edu_wpi_first_networktables_NetworkTablesJNI_now
+  (JNIEnv*, jclass)
+{
+  return wpi::Now();
+}
+
 /*
  * Class:     edu_wpi_first_wpiutil_WPIUtilJNI
  * Method:    addPortForwarder